Many automotive vehicles, including most American-made cars, have their gas tank inlet spouts and caps located behind the rear license plate and the backing plate to which the license plate is attached. The backing plate is usually hinged at its bottom or top to the frame of the vehicle. The license plate is then attached to the backing plate by one of many available means (i.e. bolts, clips, etc. ). The hinge is biased such that it holds the backing plate and the license plate in a vertical (closed) position and rotates the backing plate and license plate to their closed position (abutting the vehicle) whenever the license plate and backing plate are rotated out of this position.
To put gas in a vehicle as described above, one must pull down or up the backing plate and the license plate to a down or up or horizontal (open) position, and while holding the plates in this position, unscrew the gas cap, remove the gas cap and place it on the ground, the trunk of the vehicle, etc.; and then place the gas pump hose spout into the gas tank inlet spout. If the license plate and backing plate are then released, they will rest on the gas pump hose spout in a partially open position. If the gas pump hose spout does not have a device to keep the hose valve open until the gas tank is full, then one must keep one's hand on the gas activating level while filling the gas tank and the plates interfere with the hand.
When the desired amount of gas has been put into the gas tank, one must again depress the backing plate and license plate (which have been held open by the gas pump hose handle) to remove the gas pump hose spout and put the gas cap back on the end of the gas tank inlet spout.
As can be seen from the above, the inability to lock the backing plate and license plate in an open position causes these plates to always be in the way when one is putting gas into a vehicle's gas tank. Sometimes, persons putting gas into a car with the gas tank inlet spout located as described above, will jam the gas cap between the backing plate and the vehicle to hold open the backing plate. The gas cap can be easily dropped to the ground or otherwise damaged when utilized in this manner. Other persons may try and prop their knee, arm, etc. against the license plate and/or backing plate to hold them open. Holding the plates open in this manner may soil one's clothes or may cause the person to sustain minor cuts and bruises if the edges of the backing plate and license plate are jagged and/or if the person loses his balance while trying to maneuver to hold the plates open.